Compare PDF
What changed between two versions of a document, word for word and page by page.
Drop files here
or click to choose from your deviceAccepted: PDF
Up to 3 files per runUp to 20 MB per file5 runs per dayFree PDFs end with a small “Made with nouplo.com” lineRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Worked example — Compare PDF
Use the following inputs and settings.
| Item | Value |
|---|---|
| Input | one.pdf · 1 · A4 · HELLO WORLD |
| Input | two.pdf · 1 · A4 · Changed text |
| Compare | The words (documents, contracts) |
| Output files | 2 |
| Output | two-changes.txt |
| Output | two-compared.pdf |
| PDF pages | 1 |
Expected result — Output files: 2.
How it works
- Drop the two PDFs: the old version first, then the new one. The order in the list decides which is which; drag to swap them.
- Leave "The words" for documents with text. Choose "The pages as pictures" for drawings, designs and scans.
- Select Compare. The changes appear as a list, each with the words around it, the old wording and the new, and the page.
- Download the side-by-side PDF to see them in place: removed words red on the old version, added words green on the new.
Frequently asked questions
- How does it decide what changed?
- The text of both PDFs is split into words (characters, in Japanese and Chinese) and compared in order, the way a document comparison in a word processor does. A reworded clause shows as the old words removed and the new ones added; a page added in the middle stands on its own while the pages around it stay paired.
- Can it compare scanned PDFs?
- As pictures, yes: each page is rendered and the two versions are compared pixel by pixel, and every region that differs is framed on both. It cannot tell which words changed on a scan; run Make PDF searchable on both first if you need that.
- Why are some changes that do not look like changes listed?
- Because the text behind them differs: a word split by a line break in one version, a page number that moved with an added page, or a character that looks the same but is a different one (a different dash, for example). They are real differences in the file, even when the page looks alike.
- Are my files uploaded, and what are the free limits?
- No: both PDFs are read in your browser. The free plan compares PDFs of up to 20 MB each, 5 times a day, and adds a small "Made with nouplo.com" line to the side-by-side PDF. Pro removes the line and the limits.
Related tools
¶ PDF OCR Scans become text you can copy and search, without the document leaving your device. ⧉ Merge PDF Combine PDFs into one document, in the order you choose, without sending them anywhere. ▦ Organize PDF pages Delete, reorder and rotate pages visually, all in one go, without sending the document anywhere. ▬ Redact PDF Black out what must not be shared and have it actually gone from the file, without uploading the document.